1. Field of the Invention
The present invention relates to a method and an apparatus for diagnosing a photovoltaic power system provided in a house, or the like and, in particular to a diagnosis method and a diagnosis apparatus of a photovoltaic power system which diagnoses the normality/abnormality of the output and which, if necessary, diagnoses the cause of the abnormality.
2. Description of the Related Art
Conventionally, photovoltaic power, which has very little effect on the earth's environment and which generates electricity through the use of solar energy has been considered the most promising clean energy for the future, unlike thermal power generation in which fossil fuels undergo combustion and in which large amounts of carbon dioxide are discharged leading to global warming, hydroelectric power generation which has the difficulty of securing installation sites or atomic power generation which has the problem of the disposal of waste, or the like. In recent years, the spread to residential houses of the photovoltaic power system has expanded in accordance with the introduction of financial assistance from public organizations.
Such a photovoltaic power system comprises a solar battery panel, having a plurality of solar battery cells electrically connected in series, which is mounted on a roof, or the like; an inverter, which converts the direct current output from the solar battery panel to an alternating current output; and wires, which make connections between the solar battery panel and the inverter as well as between the inverter and the loads. Then, when the solar rays irradiate the solar battery panel, a photovoltaic conversion is carried out in each solar battery cell and these conversion outputs are collected so as to generate direct current power and, then, this direct current power is converted to alternating current power by the inverter so as to be supplied to the loads.
In order to stably gain a desired electric energy to be supplied to the loads, it is necessary to monitor whether or not the photovoltaic power system operates normally so as to take measures after quickly discovering the cause in the case that it is found that the output is abnormal. However, a system wherein the diagnosis, of whether or not the operation of the photovoltaic power system is normal, is carried out simply and with a high precision has not yet been constructed. Though a variety of methods for detecting abnormalities of each component of a solar power system have been conventionally known, there is a problem that, in the case that the output of the photovoltaic power system is abnormal, the work of the discovery of the cause by inspecting each component using such methods takes a long period of time. In addition, there is a problem in that the work of the discovery of the cause cannot be carried out in the case that the output of the system becomes abnormal in spite of the fact that each component operates normally.